Hunt for Girls After Alleged Dad Threat

Police in Florida are searching for two young girls after their parents allegedly made a suicide pact to kill the family as they struggle to treat one of the girls' autism.

James Firth, 43, and wife Mai Firth, 31, traveled to Florida from Vietnam, where they had been living with their two girls, Trieu "Kiah" Co Firth, 2, and Chieu "Kristin" Quan Firth, 4. The couple were seeking treatment for autistic daughter Kristin at the Florida Institute of Technology in Melbourne, Fla., police said.

"They were at that center, they were dealing with staff there, when the father made mention that if the child's treatment didn't show improvement, or if they ran out of money, they'd kill themselves," Sgt. Sheridan Shelley of the Melbourne police department told ABCNews.com.

The family then vanished Thursday, and a missing-child alert has been issued for the girls. They were last seen with their parents in Melbourne at the university. James Firth has family in nearby Ormond Beach, Fla., officials said.

The couple made the alarming statements to professionals in Florida with whom they'd had contact while seeking treatment for Kristin, Carrie Hoeppner of the Florida Department of Child Services told ABC News.com.

That's when the agency tracked them down.

"When the report was generated to our agency, we made contact with the family. We had eyes on the kids," Hoeppner said. "During the investigation, the family left against the request of investigators, which prompted us to call law enforcement."

James Firth lied to police about the hotel where the family was staying while they sought treatment for Kristin before the four disappeared, Sgt. Shelley said. As of today, he added, no criminal charges have been filed, but the family will have to go before a judge after they are found.

"There is now a judge's order because of the statements made, and concern for the children's welfare," he said.

Florida Child Services wants to interview the family in person, Shelly said. If they are uncomfortable speaking with representatives from the department, they can go straight to the judge.

"All we want is the welfare of the children to be checked out," he said. "And the entire family. We want to ensure parents are OK as well.

Authorities are unsure of the family's whereabouts but said that Firth has family in Florida, Michigan and Arizona. Authorities said that they might be traveling in a silver 2002 Lexus SUV.

Anyone with information about the family's whereabouts is asked to call Melbourne police or Crimeline at 1-800-423-TIPS (8477).